UNIVERSITY    OF   CALIFORNIA 

COLLEGE    OF    AGRICULTURE 

AGRICULTURAL   EXPERIMENT   STATION 

CIRCULAR  No.  274 
January,  1924 

Fusarium  Wilt  of  Tomato  and  Its  Control  by 
Means  of  Resistant  Varieties 

BY 
J.  W.  LESLEY 


Wilt  is  among  the  most  serious  diseases  of  the  tomato  in  California, 
often  inflicting  considerable  loss  both  on  the  shipping  and  on  the  can- 
ning crop.  It  is  exceptional  to  find  a  field  entirely  free  from  wilt, 
and  cases  frequently  occur  where  from  5  to  10  per  cent,  and  occasion- 
ally as  much  as  85  per  cent,  of  the  crop  is  lost.  The  disease  varies 
considerably  in  severity  in  different  seasons.  For  instance,  in  the 
Santa  Clara  Valley  it  was  more  severe  in  1922  than  in  1923.  As  a 
rule,  wilt  is  more  important  than  Western  blight  in  regions  near  the 
coast,  such  as  Orange  County  and  the  San  Fernando  and  Santa  Clara 
valleys. 

The  cause  of  wilt  is  a  fungus  (Fusarium  Lycopersici  Sacc.)  which 
inhabits  the  soil  and  invades  the  young  roots  of  the  tomato  plants. 
The  plants  may  become  infected  either  in  the  seedbed  or  in  the  field 
after  transplanting.  The  wilt  fungus  is  rather  widely  scattered  in 
the  tomato  growing  sections  of  the  state.  Once  present  in  any  part 
of  a  field,  it  tends  to  spread,  especially  if  the  land  is  cropped  to 
tomatoes  at  short  intervals  or,  still  worse,  without  rotation. 

Very  often  wilt  is  referred  to  as  "blight,"  in  spite  of  the  fact  that 
the  two  diseases  are  quite  distinct  and  are  easily  distinguished  even 
when  the  same  plant  is  attacked  by  both.  In  view  of  this  confusion, 
a  description  of  the  characteristic  symptoms  of  wilt  is  included  here. 

FUSARIUM   WILT  SYMPTOMS    IN   CALIFORNIA 

Once  the  wilt  fungus  has  gained  entrance  into  the  roots  of  the 
tomato  plant,  is  grows  up  through  the  woody  part  of  the  vascular 
bundles  into  the  stem,  sometimes  for  a  considerable  distance.  Corre- 
sponding to  the  growth  of  the  fungus  from  below  upwards,  a  yellow 


Z  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

discoloration  of  the  lowest  leaves  occurs,  usually  giving  the  first  indi- 
cation of  the  disease.  As  the  disease  develops,  the  lower  leaves  turn 
brown  and  the  upper  leaves  often  appear  unusually  dark  green,  while 
the  leaflets  become  curled  downward  and  shrunken.  If  the  progress 
of  the  disease  is  very  rapid,  some  wilting  of  young  leaves  occurs,  as 
the  name  of  the  disease  indicates,  but  the  wilted  condition  is  by  no 
means  always  present.  In  this  stage  the  affected  plants  appear  as 
if  suffering  from  lack  of  water.  A  good  indication  of  wilt  is  the 
browning  of  the  woody  tissues  of  the  stems  and  roots,  best  seen  by 
cutting  or  splitting  the  main  stem  near  the  ground.  The  discoloration 
usually  does  not  extend  into  the  pith  or  central  part  of  the  stem  until 
the  final  decay  sets  in. 

It  is  common  with  this  disease  to  find  that,  while  some  of  the  stems 
of  the  tomato  plant  are  diseased,  the  remainder  appear  quite  healthy. 
One  side  of  a  stem  may  even  show  browning  of  the  wood,  while  the 
other  side  appears  healthy  and  free  from  discoloration.  Diseased 
plants  often  put  out  new  and  healthy  shoots;  these  however  in  turn 
may  become  infected.  In  the  final  stage  of  a  serious  case  of  wilt  the 
plant  turns  brown,  dries  up,  and  dies.  Those  affected  plants  which 
continue  to  live  through  the  season  produce  some  fruit.  The  yield, 
however,  is  much  reduced  and  the  fruit  undersized,  although  the 
seeds  usually  mature.  If  seedlings  become  infected  while  in  the  seed- 
bed, they  may  perish  early,  or  if  transplanted  to  the  field,  are  likely 
to  die  without  producing  any  crop. 


PREVENTIVE    MEASURES 

Since  the  infection  occurs,  as  a  rule,  either  in  the  seedbed  or  in 
the  field,  the  greatest  care  should  be  taken  to  select  land  which  is  free 
from  the  wilt  fungus.  If  the  seedlings  show  any  " damping  off"  or 
11  collar  rot,"  the  seedbed  should  not  be  used  another  year.  Plants 
from  such  a  seedbed  are  likely  to  develop  wilt.  Even  if  no  disease 
is  observed,  the  repeated  use  of  the  same  seedbed  year  after  year  is 
not  a  good  practice.  Infection  with  wilt  in  the  seedbed  (as  with  some 
other  diseases)  usually  has  far  worse  consequences  than  infection  in 
the  field.  The  practice  of  buying  plants  should,  if  possible,  be  avoided, 
as  such  plants  are  frequently  the  means  of  introducing  some  disease. 

It  is  difficult  to  be  sure  that  a  field  for  tomatoes  is  entirely  free 
from  disease,  and  sometimes  it  is  necessary  to  plant  in  a  field,  in 
which  some  infection  is  present.  Consequently,  some  means  of  control 
must  be  sought.     Once  the  plants  are  set  out,  no  control  measures 


Circular  274] 


TOMATO  WILT  AND  ITS   CONTROL 


Fig.  1. — Healthy  tomato  plant. 


Fig.  2.— Tomato  plant  affected  with  Fusarium  wilt.     Branch  to  left  wilted ;  to 
right  dried  up  from  disease.     Healthy  growth  in  center. 


4  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

avail.  Treatment  of  the  soil  before  planting  with  fungicides  such  as 
formaldehyde  is  costly  and  not  practicable  except  on  a  small  area. 
Rotation  of  crops,  however,  is  advisable  as  it  affords  some  protection 
against  wilt.  If,  for  example,  tomatoes  are  planted  once  in  three 
years,  the  wilt  disease  will  probably  cause  less  damage  than  if  tomatoes 
are  planted  more  frequently.  But  it  should  be  noted  that  the  fungus 
is  not  solely  dependent  on  tomato  plants  for  its  maintenance.  It  may 
live  for  one  or  more  years  on  decayed  organic  matter  in  the  soil, 
only  to  reappear  when  tomatoes  are  planted  there  again.  Crops  such 
as  watermelons,  peppers,  and  potatoes  are  not  likely  to  be  affected 
by  the  tomato  wilt,  although  these  crops  may  suffer  from  wilts  caused 
by  closely  related  fungi. 

WILT    RESISTANT   VARIETIES 

The  best  method  of  control  is  the  use  of  wilt  resistant  varieties. 
This  method  is  being  successfully  applied  in  many  tomato  growing 
states  in  which  wilt  has  caused  serious  loss.  Such  varieties  are  not 
entirely  proof  against  the  disease.  On  the  contrary,  they  become 
infected  but  are  able  to  produce  a  satisfactory  crop  in  spite  of  it. 

At  the  present  time,  the  variety  most  widely  grown  in  southern 
California  and  in  the  San  Joaquin  Valley  is  Stone.  This  variety  is 
very  susceptible  to  wilt.  San  Jose  Canner,  a  variety  with  large  well- 
shaped  fruits  (not  to  be  confused  with  the  so-called  "Jap,  Canner") 
is  also  very  susceptible.  The  same  is  true  of  Earliana,  a  variety  grown 
to  a  considerable  extent  for  the  local  market.  Probably  these  three 
varieties  are  used  on  more  than  half  of  the  tomato  acreage  of  the 
state,  and  none  of  them  is  resislflnt  to  wilt.  They  are  in  many 
respects  well  suited  to  the  sections  in  which  they  are  grown  and 
often  produce  heavy  crops,  but  being  susceptible  to  wilt,  they  are 
not  suitable  for  planting  on  wilt  infected  land.  Indeed,  such  a  prac- 
tice may  lead  to  serious  loss  as  some  recent  experiments  clearly 
indicate. 

During  the  season  of  1923  many  tomato  varieties  reported  to  be 
wilt-resistant  in  other  states  were  tested  on  plots  situated  at  Riverside, 
La  Mesa  in  San  Diego  County,  and  at  Chatsworth  in  the  San  Fer- 
nando Valley.  One  variety  named  Norton  which  proved  wilt  resistant 
at  all  three  places  may  be  recommended  for  commercial  planting  in 
place  of  the  Stone  wherever  wilt  disease  has  been  at  all  troublesome. 

Norton  originated  as  a  selection  from  Stone  and  closely  resembles 
the  parent  variety.  The  principal  difference  lies  in  the  fact  that 
Stone  is  very  susceptible  to  wilt,  whereas  Norton  is  resistant.     In 


Circular  274]  TOMATO  WILT  AND  ITS  CONTROL  5 

1923,  in  a  field  in  San  Diego  County  which  was  severely  infected  with 
wilt,  the  variety  Stone  was  practically  a  total  failure,  but  Norton, 
growing  on  the  same  field,  gave  a  satisfactory  crop.  Even  on  land 
free  from  infection  Norton  gives  results  equal  to  Stone.  For  instance, 
in  1923,  a  large  grower  in  the  San  Fernando  Valley  who  planted 
some  thirty  acres  of  this  variety  in  a  field  almost  free  from  wilt 
infection,  reports  that  Norton,  although  somewhat  smaller  in  size, 
was  at  least  equal  to  Stone  in  production  and  seemed  to  have  some- 
what heavier  fruit.  If  the  wilt  disease  had  been  prevalent  in  this 
field,  as  was  often  the  case  in  1923  in  the  San  Fernando  Valley,  Norton 
would  have  given  much  the  larger  crop. 

It  should  be  noted  that  resistance  to  wilt  by  no  means  indicates 
any  resistance  to  Root  Knot  (Nematode)  or  to  Western  blight. 
Although  Norton  is  recommended  for  planting  in  sections  where 
Stone  is  now  grown,  it  may  not  be  suitable  for  other  sections,  such 
as  the  Santa  Clara  Valley  where  the  "  Jap,  Canner"  variety  is  now 
largely  grown.  It  is  not  yet  possible  to  recommend  a  wilt  resistant 
variety  fully  adapted  to  the  conditions  of  the  Santa  Clara  Valley  or 
other  northern  coastal  sections,  but  it  is  hoped  in  time  to  develop 
from  the  "  Jap,  Canner"  a  more  wilt  resistant  selection. 

Several  other  promising  varieties  showed  wilt  resistance  in  the 
recent  trials  in  California.  Among  them  is  the  well  known  Globe 
variety,  which  is  earlier  in  maturing  than  Stone  but  later  than 
Earliana.  It  has  pink  fruit  of  exceptionally  good  shape  but  con- 
siderably smaller  in  size  than  Stone.  The  foliage  is  rather  scanty, 
thus  making  the  fruit  more  subject  to  sunburn.  Being  earlier  than 
Stone,  wilt  resistant,  a  good  shipper,  and  prolific,  Globe  may  be  used 
to  advantage  under  suitable  conditions. 

Certain  other  varieties  have  also  shown  indications  of  resistance 
to  wilt  disease  but  need  further  trial  of  their  wilt  resistance  and 
other  qualities  before  any  of  them  can  be  recommended  for  planting. 
Some  of  the  most  promising  may  be  mentioned  here.  Marvel  appeared 
to  be  remarkably  wilt  resistant  and  produced  a  good  crop  on  heavily 
infested  land.  It  bears  scarlet  fruit  of  good  shape  but  smaller  than 
Stone  although  earlier  in  maturity.  Louisiana  Red  and  Louisiana 
Pink  were  also  wilt  resistant.  These  varieties  produced  good  yields 
of  early  maturing  fruit,  that  of  Louisiana  Pink  being  larger  in  size. 
As  with  other  early  varieties  the  vines  were  rather  scanty.  Norduke 
also  seemed  to  be  very  resistant  to  wilt.  This  variety  matured  later 
and  was  not  equal  to  Norton  in  production.  It  bears  scarlet  fruit 
equal  to  Stone  in  size  and  the  vines  are  exceptionally  luxuriant,  thus 
affording  ample  shade  for  the  fruit. 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


SUMMARY 

Wilt  disease  of  tomatoes,  caused  by  the  fungus  Fusarium  Lyco- 
persici  Sacc,  inflicts  serious  losses  on  tomato  fields  in  California.  Soil 
of  the  tomato  seedbeds  should  be  free  from  the  fungus,  as  infection 
in  the  seedbed  is  destructive  to  the  young  plants  and  is  often  the 
means  of  spreading  the  disease  to  uninfected  fields.  If  the  field  is 
already  infected,  a  rotation  of  crops  is  advisable.  When  an  infected 
field  is  to  be  cropped  to  tomatoes,  wilt  resistant  varieties  should  be 
used. 

In  sections  where  Stone  is  now  the  standard  variety,  Norton  is 
recommended  in  preference,  as  it  is  resistant  to  wilt  and  is  a  desirable 
commercial  variety.  Globe  has  also  shown  wilt  resistance  and  under 
suitable  conditions  may  be  useful  where  a  somewhat  earlier  variety 
for  shipping  is  desired. 


STATION  PUBLICATIONS  AVAILABLE  FOE  FREE  DISTRIBUTION 


No. 

253.  Irrigation  and  Soil  Conditions  in  the 
Sierra  Nevada  Foothills,  California. 

261.  Melaxuma    of    the    Walnut,    "Juglans 

regia." 

262.  Citrus  Diseases   of  Florida   and   Cuba 

Compared  with  those  of  California. 

263.  Size  Grades  for  Ripe  Olives. 

268.   Growing  and  Grafting  Olive  Seedlings. 
273.   Preliminary  Report  on   Kearney  Vine- 
yard Experimental  Drain. 

275.  The  Cultivation  of  Belladonna  in  Cali- 

fornia. 

276.  The   Pomegranate. 

277.  Sudan  Grass. 

278.  Grain   Sorghums. 

279.  Irrigation  of  Rice  in  California, 

280.  Irrigation  of  Alfalfa  in  the  Sacramento 

Valley. 
283.  The  Olive  Insects  of  California. 

285.  The  Milk  Goat  in  California. 

286.  Commercial   Fertilizers. 

287.  Vinegar  from  Waste  Fruits. 
294.  Bean  Culture  in  California. 
298.   Seedless  Raisin  Grapes. 

804.  A  Study  of  the  Effects  of  Freezes  on 
Citrus   in   California. 

308.  I.  Fumigation  with  Liquid  Hydrocyanic 
Acid.  II.  Physical  and  Chemical  Prop- 
erties of  Liquid  Hydrocyanic  Acid. 

312.  Mariout  Barley. 

317.  Selections  of  Stocks  in  Citrus  Propa- 
gation. 

319.  Caprifigs  and  Caprification. 

321.   Commercial  Production  of  Grape  Syrup. 

324.  Storage  of  Perishable  Fruit  at  Freezing 

Temperatures. 

325.  Rice  Irrigation  Measurements  and  Ex- 

periments    in     Sacramento  •   Valley, 

1914-1919. 
328.   Prune  Growing  in  California. 
331.   Phylloxera-Resistant   Stocks. 

334.  Preliminary  Volume  Tables  for  Second- 

Growth  Redwood. 

335.  Cocoanut    Meal    as    a    Feed    for   Dairy 

Cows  and  Other  Livestock. 

336.  The   Preparation   of   Nicotine  Dust   as 

an  Insecticide. 


BULLETINS 

No. 


339. 

341. 
343. 
344. 

346. 
347. 

348. 
349. 

350. 
351. 
352. 

353. 
354. 
355. 
357. 


358. 

359. 
360. 

361. 

862. 
363. 

364. 

366. 

367. 

368. 

369. 
370. 
371. 


The  Relative  Cost  of  Making  Logs  from 
Small    and    Large   Timber. 

Studies  on  Irrigation  of  Citrus  Groves. 

Cheese  Pests  and  Their  Control. 

Cold  Storage  as  an  Aid  to  the  Market- 
ing of  Plums. 

Almond  Pollination. 

The  Control  of  Red  Spiders  in  Decidu- 
ous Orchards. 

Pruning  Young  Olive  Trees. 

A    Study    of    Sidedraft    and    Tractor 
Hitches. 

Agriculture  in  Cut-over  Redwood  Lands. 

California  State  Dairy  Cow  Competition. 

Further  Experiments  in  Plum  Pollina- 
tion. 

Bovine  Infectious  Abortion. 

Results  of  Rice  Experiments  in  1922. 

The  Peach  Twig  Borer. 

A    Self-mixing    Dusting    Machine 
Applying      Dry       Insecticides 
Fungicides. 

Black     Measles,     Water    Berries, 
Related    Vine    Troubles. 

Fruit  Beverage  Investigations. 

Gum  Diseases  of  Citrus  Trees  in  Cali- 
fornia. 

Preliminary   Yield   Tables   for   Second 
Gvowth  Redwood. 

Dust  and  the  Tractor  Engine. 

The  Pruning  of  Citrus  Trees  in  Cali- 
fornia. 

Fungicidal   Dusts   for   the   Control   of 
Bunt. 

Turkish  Tobacco  Culture,  Curing  and 
Marketing. 

Methods  of  Harvesting  and  Irrigation 
in  Relation  to  Mouldy  Walnuts. 

Bacterial  Decomposition  of  Olives  dur- 
ing Pickling. 

Comparison  of  Woods  for  Butter  Boxes 

Browning:  of  Yellow  Newtown  Apples. 

The    Relative    Cost   of    Yarding    Small 
and  Large  Timber. 


for 
and 


and 


CIRCULARS 

No.  No. 
70.  Observations    on    the    Status   of    Corn  161. 
Growing  in  California.  164. 
87.  Alfalfa.  165. 
111.  The  Use  of  Lime  and  Gypsum  on  Cali- 
fornia Soils.  166. 
113.  Correspondence  Courses  in  Agriculture.  167! 
117.  The    Selection    and    Cost    of    a    Small  170! 

Pumping  Plant. 

136.  Melilotua    vndica    as    a    Green-Manure  172. 

Crop  for  California.  173. 
127.   House  Fumigation. 

129.  The  Control  of  Citrus  Insects.  174. 

144.   Oidium  or  Powdery  Mildew  of  the  Vine.  175. 

151.  Feeding  and  Management  of  Hogs. 

152.  Some    Observations  on  the  Bulk    Hand-  178. 

ling;  of  Grain   in    California.  179, 

153.  Announcement  of  the  California  State 

Dairy  Cow  Competition,   1916-18.  182. 

154.  Irrigation  Practice  in   Growing   Small 

Fruit  in  California.  184. 

155.  Bovine  Tuberculosis.  188. 

157.  Control  of  the  Pear  Scab.  190. 

158.  Home  and  Farm  Canning.  193 
160.   Lettuce  Growing  in  California.  198 


Potatoes  in   California. 

Small  Fruit  Culture  in  California. 

Fundamentals   of    Sugar   Beet   Culture 

under  California  Conditions. 
The  County  Farm  Bureau. 
Feeding  Stuffs  of  Minor  Importance. 
Fertilizing  California  Soils  for  the  1918 

Crop. 
Wheat  Culture. 
The    Construction    of   the    Wood-Hoop 

Silo. 
Farm   Drainage  Methods. 
Progress  Report  on  the  Marketing  and 

Distribution   of  Milk. 
The  Packing  of  Apples  in  California. 
Factors    of    Importance    in    Producing 

Milk  of  Low  Bacterial  Count. 
Extending  the  Area  of  Irrigated  Wheat 

in    California   for  1918. 
A  Flock  of  Sheep  on  the  Farm. 
Lambing   Sheds. 

Agriculture  Clubs   in   California. 
A  Study  of  Farm  Labor  in  California. 
Syrup  from  Sweet  Sorghum. 


CIRCULARS — Continued 


No. 
199. 
201. 
202. 

203. 
205. 
206. 
208. 

209. 
210. 
212. 
214. 

215. 
217. 

218. 

219. 
228. 
230. 

231. 
232. 

233. 
234. 

235. 

236. 


237. 

238. 
239. 

240. 

241. 


Onion  Growing  in  California. 

Helpful  Hints  to  Hog  Raisers. 

County  Organizations  for  Rural  Fire 
Control. 

Peat  as  a  Manure  Substitute. 

Blackleg. 

Jack  Cheese. 

Summary  of  the  Annual  Reports  of  the 
Farm  Advisors  of  California. 

The  Function  of  the  Farm  Bureau. 

Suggestions  to  the  Settler  in  California. 

Salvaging  Rain-Damaged  Prunes. 

Seed  Treatment  for  the  Prevention  of 
Cereal  Smuts. 

Feeding  Dairy  Cows  in  California. 

Methods  for  Marketing  Vegetables  in 
California. 

Advanced  Registry  Testing  of  Dairy 
Cows. 

The  Present  Status  of  Alkali. 

Vineyard  Irrigation  in  Arid  Climates. 

Testing  Milk,  Cream,  and  Skim  Milk 
for  Butterfat. 

The  Home  Vineyard. 

Harvesting  and  Handling  California 
Cherries  for  Eastern  Shipment. 

Artificial  Incubation. 

Winter  Injury  to  Young  Walnut  Trees 
during  1921-22. 

Soil  Analysis  and  Soil  and  Plant  Inter- 
relations. 

The  Common  Hawks  and  Owls  of  Cali- 
fornia from  the  Standpoint  of  the 
Rancher. 

Directions  for  the  Tanning  and  Dress- 
ing of  Furs. 

The  Apricot  in  California. 

Harvesting  and  Handling  Apricots  and 
Plums  for  Eastern  Shipment. 

Harvesting  and  Handling  Pears  for 
Eastern   Shipment. 

Harvesting  and  Handling  Peaches  for 
Eastern  Shipment. 


No. 
243. 

244. 
245. 
247. 
248. 

249. 
250. 

251. 


252. 
253. 
254. 

255. 

256. 
257. 
258. 
259. 
260. 

261. 
262. 
263. 
264. 

265. 
266. 

267. 

268. 

269. 
270. 
271. 


Marmalade  Juice  and  Jelly  Juice  from 
Citrus  Fruits. 

Central  Wire  Bracing  for  Fruit  Trees. 

Vine  Pruning  Systems. 

Colonization  and  Rural  Development. 

Some  Common  Errors  in  Vine  Pruning 
and  Their  Remedies. 

Replacing  Missing  Vines. 

Measurement  of  Irrigation  Water  on 
the  Farm. 

Recommendations  Concerning  the  Com- 
mon Diseases  and  Parasites  of 
Poultry    in    California. 

Supports  for  Vines. 

Vineyard   Plans. 

The  Use  of  Artificial  Light  to  Increase 
Winter  Egg  Production. 

Leguminous  Plants  as  Organic  Fertil- 
izer in  California  Agriculture. 

The  Control  of  Wild  Morning  Glory. 

The  Small-Seeded  Horse  Bean. 

Thinning  Deciduous  Fruits. 

Pear  By-products. 

A  Selected  List  of  References  Relating 
to  Irrigation  in  California. 

Sewing  Grain  Sacks. 

Cabbage  Growing  in  California. 

Tomato  Production  in  California. 

Preliminary  Essentials  to  Bovine  Tuber- 
culosis Control. 

Plant  Disease  and  Pest  Control. 

Analyzing  the  Citrus  Orchard  by  Means 
of  Simple  Tree  Records. 

The  Tendency  of  Tractors  to  Rise  in 
Front:  Causes  and  Remedies. 

Inexpensive  Labor-saving  Poultry  Ap- 
pliances. 

An  Orchard  Brush  Burner. 

A  Farm  Septic  Tank. 

Brooding  Chicks  Artificially. 


10m-5/24 


